Methods for forming dental prosthesis

Abstract

A dental prosthesis is formed by attaching an internally threaded sleeve to a post by means of heat-meltable material. A dimensionally stable, heat-meltable material is applied to the post and around the sleeve. The heat-meltable materials are melted and replaced by a permanent material. A screw is inserted into the sleeve prior to the melting step. The melting and replacing steps comprise steps in an investment-type casting procedure wherein a unit comprised of the post, the sleeve, the screw, and the heat-meltable materials is embedded in an investment material such that a head of the screw is embedded in the investment material to maintain the positional relationship of the sleeve relative to the post during the melting step. A release material is applied over a body defined by the permanent material. A dimensionally stable, heat-meltable material is applied over the release material and is melted and replaced with a permanent material which forms an overlay capable of being removed upon removal of the screw.

What I claim is: 
     
       1. A method of forming a dental prosthesis comprising the steps of: attaching an internally threaded sleeve to a post,   applying a dimensionally stable, heat-meltable material to said post and around said sleeve without covering an open end of said sleeve with said heat-meltable material, and   melting said heat-meltable material and replacing same with a permanent material such that said open end of said sleeve remains uncovered by said permanent material.   
     
     
       2. A method according to claim 1, wherein said sleeve is attached to a post by means of a heat-meltable material. 
     
     
       3. A method according to claim 1 including the step of threadedly inserting a screw into said sleeve prior to said melting step, said melting and replacing steps comprising steps in an investment-type casting procedure wherein a unit comprised of said post, said sleeve, said screw, and said heat-meltable material is embedded in investment material such that a head of said screw is embedded in said investment material to maintain the positional relationship of said sleeve relative to said post during said melting step. 
     
     
       4. A method according to claim 3 including the steps of applying dimensionally stable, heat-meltable material over a body defined by said permanent material, removing said last-named heat-meltable material from said body, melting said last-named meltable material and replacing it with a permanent material which forms an overlay capable of being removably attached to said body by means of said screw. 
     
     
       5. A method according to claim 4 including the step of applying a release material to said body before applying said last-named heat-meltable material. 
     
     
       6. A method according to claim 1, wherein said post comprises a portion of a pin which includes a flange and an externally threaded stem, said post projecting from one side of said flange, and said stem projecting from an opposite side of said flange, said dimensionally stable, heat-meltable material being applied upon said one side of said flange during said applying step, said stem adapted to be threaded into a threaded hole of a jaw anchor. 
     
     
       7. A method of forming a dental prosthesis and securing same in the jaw bone of a patient, comprising the steps of: drilling a bore in the patient's jaw bone,   inserting into said bore an anchor formed of a material which is biocompatible with bone tissue, said anchor including an internally threaded opening accessible from within the patient's mouth,   inserting into said threaded opening an externally threaded stem of a pin, said pin including a flange having a first side from which said stem projects and a second side from which a post extends in a direction opposite said stem, such that said flange seats upon said anchor and said post projects away from said anchor,   forming an impression of at least a portion of said jaw including said post, such that said post forms a cavity in said impression,   removing said pin from said anchor and inserting said post into said cavity such that said threaded stem extends away from said impression,   pouring a hardenable substance into said impression to form a dental model in which said stem is disposed,   attaching to said post a fastener assembly comprising an internally threaded sleeve and a screw threaded therein,   forming upon said flange and around said post and sleeve a shaped mass of dimensionally stable, heat-meltable material, and   melting said heat-meltable material and replacing same with a permanent material to form a permanent body.   
     
     
       8. A method according to claim 7, including the steps of applying a dimensionally stable heat-meltable material over said permanent body, removing said last-named heat-meltable material from said permanent body, melting said last-named heat-meltable material and replacing it with a permanent material which forms an overlay capable of being removably attached to said permanent body by said screw. 
     
     
       9. A method according to claim 7, wherein said sleeve is attached to said post by means of a heat-meltable material which is melted and replaced with said permanent material. 
     
     
       10. A method according to claim 7, wherein said melting step includes embedding said pin, said mass, and said fastener assembly in investment material whereby a head of said screw is embedded in said investment material to maintain the positional relationship of said fastener assembly relative to said post during said melting step. 
     
     
       11. A method according to claim 7, wherein said post comprises a portion of a pin which includes a flange and an externally threaded stem, said post projecting from one side of said flange, and said stem projecting from an opposite side of said flange, said dimensionally stable, heat-meltable material being applied upon said one side of said flange during said applying step, said stem adapted to be threaded into a threaded hole of a jaw anchor. 
     
     
       12. A method according to claim 7, wherein said post is of non-symmetrical, non-circular cross-sectional shape such that said cavity formed in said impression is of a similar cross-sectional shape. 
     
     
       13. A method of forming a dental prosthesis, comprising the steps of: drilling a bore in a patient's jaw bone,   inserting into said bore an anchor formed of a material which is biocompatible with bone tissue, said anchor being apertured at a front end thereof and including an internally threaded opening at a rear end thereof which is accessible from within the patient's mouth,   inserting into said threaded opening an externally threaded stem of a pin, said pin including a post extending in a direction opposite said stem, said post being of non-symmetrical, non-circular cross-section,   forming an impression of at least a portion of said jaw including said post, such that said post forms in said impression a cavity of non-symmetrical, non-circular cross-section,   removing said pin from said anchor and inserting said post into said cavity such that said threaded stem extends away from said impression,   threading a sheath onto said threaded stem,   pouring a hardenable substance into said impression to form a dental model in which said sheath is disposed, and such that said post is oriented in said model in the same position as when disposed in said anchor,   cutting said post to a desired shape while said pin is disposed in said sleeve, and   forming a body of permanent material onto said cut post.   
     
     
       14. A method according to claim 13, wherein said step of forming a body comprises attaching an internally threaded sleeve to said post, applying a dimensionally stable, heat-meltable material to said post and around said sleeve, and melting said heat-meltable material and replacing same with a permanent material. 
     
     
       15. A method according to claim 14 including the steps of applying a layer of dimensionally stable, heat-meltable material over said body, removing said layer from said body, melting said layer and replacing same with a permanent material to form an overlay capable of being removably attached to said body by means of a screw insertable through said overlay and into said threaded sleeve. 
     
     
       16. A method according to claim 13, wherein said step of forming a body of permanent material onto said cut post comprises forming upon said flange and around said post a shaped mass of dimensionally stable, heat-meltable material while said pin is disposed in said model, and melting said heat-meltable material and replacing same with a permanent material. 
     
     
       17. A method of forming a dental prosthesis comprising the steps of: providing within a dental model of a portion of a patient's jaw a pin having a flange, an externally threaded stem projecting from one side of said flange, and a post projecting from an opposite side of said flange, said post including a portion of non-circular cross-sectional shape and irregular longitudinal profile,   cutting said post to achieve a desired shape thereof while said pin is in said dental model,   forming upon said flange and around said cut post a shaped mass of dimensionally-stable, heat-meltable material while said pin is in said dental model,   removing said pin from said dental model, and   melting said heat meltable material and replacing same with a permanent material to form a body which is restrained against rotation and longitudinal movement relative to said post due to said non-circular cross-sectional shape and irregular longitudinal profile of said post.   
     
     
       18. A method according to claim 17, wherein an internally threaded sleeve is attached to said post and then said shaped mass is applied around said post and said sleeve. 
     
     
       19. A method according to claim 18 including the steps of applying a layer of dimensionally stable, heat-meltable material over said body, removing said layer from said body, melting said layer and replacing same with a permanent material to form an overlay capable of being removably attached to said body by means of a screw insertable through said overlay and into said threaded sleeve. 
     
     
       20. A method of forming a dental prosthesis and securing same in the jaw bone of a patient, comprising the steps of: drilling a bore in the patient's jaw bone, said bore including a center core of bone disposed at an inner end of said bore,   inserting into said bore an anchor formed of a material which is biocompatible with bone tissue, said anchor including an internally threaded opening accessible from within the patient's mouth,   inserting into said threaded opening an externally threaded stem of a pin, said pin including a flange having a first side from which said stem projects and a second side from which a post extends in a direction opposite said stem, said flange seating upon an end of said anchor and said post projecting away from said anchor, said post having a portion of non-symmetrical, non-circular cross-sectional shape, said flange being of larger cross-sectional size than said post and substantially the same cross-sectional size as said end of said anchor so as to cover said anchor,   forming an impression of at least a portion of said jaw including said post, such that said post forms a cavity in said impression, said cavity being of non-symmetrical, non-circular cross-sectional shape, removing said pin from said anchor and inserting said post into said cavity such that said threaded stem extends away from said impression,   installing over said threaded stem a sheath having a threaded hole which screws onto said threaded stem,   pouring a hardenable substance into said impression and around said sheath to form a dental model in which said sheath is embedded,   attaching to said post a fastener assembly comprising an internally threaded sheath and a screw threaded therein, by attaching said sleeve to said post,   forming upon said flange and around said post and sleeve a shaped mass of dimensionally stable heat-meltable material, such that said pin, said fastening assembly and said shaped mass form a preliminary unit,   encasing said preliminary unit within investing material,   melting said heat-meltable material, while maintaining said fastener assembly in position due to a head of said screw being embedded in said investing material,   replacing said melted materials with a permanent material which hardens to form a body having said sleeve embedded therein,   applying a release material over said body,   applying a layer of heat-meltable material over said release material in the shape of an overlay,   removing said layer and said screw from said release material,   encasing said layer and screw within investing material, and   melting said last-named heat-meltable material and replacing it with a permanent material which hardens to form an overlay which is removably attachable to said body by said screw.   
     
     
       21. A method of forming a dental prosthesis comprising the steps of: attaching an internally threaded sleeve to a post,   applying a dimensionally stable, heat-meltable material to said post and around said sleeve,   threadedly inserting a screw into said sleeve, and   melting said heat-meltable material and replacing same with a permanent material,   said melting and replacing steps comprising steps in an investment-type casting procedure wherein a unit comprised of said post, said sleeve, said screw, and said heat-meltable material is embedded in investment material such that a head of said screw is embedded in said investment material to maintain the positional relationship of said sleeve relative to said post during said melting step.